3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p f e a t u r e s n w i d e 8 v t o 36 v i n pu t v o l t a g e r a n g e n o u t p u t a d j u s t a b l e f r o m 1 . 25 v t o 32 v n m a x i m u m d u t y c y c l e 100 % n m i n i m u m d r o p o u t 0. 3 v n f i x e d 180 kh z s w i t c h i ng f r e qu e n c y n m a x im u m 3 . 5 a s w i t c h i ng c u rr e n t n i n t e r n a l o p t i m i ze p o w e r m o s f et n h i g h e f f i c i e n c y n e x ce ll e n t l i n e a n d l o a d r e g u l a ti o n n w i t h o u t p u t c o n s t a n t c u r r e n t l oo p n b u i l t i n t h e r m a l s h u t d o w n f u n c t i on n b u i l t i n c u rr e n t l i m i t f u n c t i on n b u i l t i n o u t p u t s h o r t p r o t e c t i o n f u n c t i on n s o p 8 - e p p ac k a ge a pp li c a t i o ns n c a r c h a r g e r n b a t t e r y c h a r g e r n l c d m o n i t o r a n d l c d t v n p o r t a b l e i n s t r u m e n t p o w e r s upp l y n t e l ec o m / n e t w o r k i n g e qu i p m e n t g e n er a l d e s cr i pt i o n t h e i s a 180 k h z f i x e d f r e qu e n c y p w m b u c k ( s t e p - d o w n ) d c / d c c o n v e r t e r , ca p a b l e o f d r i v i ng a 3 . 5 a l o a d w i t h h i g h e ff i c i e n c y , l o w r i p p l e a n d e x c e l l e n t li n e a n d l o a d r e g u l a t i o n . r e q u i r i ng a mi n i m u m n u m b e r o f e x t e r n a l c o m p o n e n t s , t h e r e gu l a t o r i s s i m p l e t o u s e a n d i n c l u d e i n t e r n a l f r e q u e n c y c o m p e n s a t i o n a n d a f i x e d - f r e qu e n c y o s c i l l a t o r . t h e p w m c o n t r o l c i r c u i t i s a b l e t o a d j u s t t h e du t y r a t i o li n ea r l y f r o m 0 t o 100 % . a n o v e r c u rr e n t p r o t e c t i o n f u n c t i o n i s b u i l t i n s i d e . w h e n s h o r t p r o t e c t i o n f u n c t i o n h a pp e n s , t h e o p e r a t i o n f r e qu e n c y w il l b e r e du ce d f r o m 180 k h z t o 48 k h z . a n i n t e r n a l c o m p e n s a t i o n b l o c k i s b u i l t i n t o mi n im i z e e x t e r n a l c o m p o n e n t c o u n t . f i gu r e 1 . p ac k a g e t y p e o f CX8517 CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 2 p i n c o n f i g u r a t i o n s f i gu r e 2 . p i n c o n f i gu r a t i o n o f ( t o p v i e w ) t a b l e 1 p i n d e s c r i p t i o n p i n n u m b er p i n n a me d e s c r i p t i o n 1 n c n o c o nn ec t e d . 2 s w p o w e r s w i t c h o u t p u t p i n ( s w ) . s w i s t h e s w i t c h n o d e t h a t s up p li e s p o w e r t o t h e o u t p u t . ( n o t e : c o nn ec t e d t h e b a c k e x p o s e d p ad t o sw . ) 3 gnd g r o u n d p i n . c a r e m u s t b e t a k e n i n l a y o u t . t h i s p i n s h o u l d b e p l ace d o u t s i d e o f t h e s c h o t t k y d i o d e t o o u t p u t ca p a c i t o r g r o u n d p a t h t o p r e v e n t s w i t c h i ng c u rr e n t s p i k e s f r o m i n d u c i ng v o l t a g e n o i s e i n t o . 4 f b f ee d b a c k p i n ( f b ) . t h r o ug h a n e x t e r n a l r e s i s t o r d i v i d e r n e t w o r k , f b s e n s e s t h e o u t p u t v o l t a g e a n d r e gu l a t e s i t . t h e f ee d b ac k t h r e s h o l d v o l t a g e i s 1 . 25 v . 5 e n e n a b l e p i n . d r i v e e n p i n l o w t o t u r n o ff t h e d e v i ce , d r i v e i t h i g h t o t u r n i t o n . 6 o c s et o u t p u t c o n s t a n t c u r r e n t s e t p i n . 7 v c i n t e r n a l v o l t a g e r e g u l a t o r b y p a ss c a p a c i t y . i n t y p i c a l s y s t e m a p p li ca t i o n , t h e v c p i n c o n n ec t a 1u f ca p a c i t y t o v i n . 8 v i n s up p l y v o l t a g e i n pu t p i n . o p e r a t e s f r o m a 8 v t o 36 v d c v o l t a g e . b y p a s s v i n t o gn d w i t h a s u i t a b l y l a r g e ca p a c i t o r t o e l im i n a t e n o i s e o n t h e i n pu t . t h e e x p o s e d p a d i s s w CX8517 CX8517 CX8517 CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 3 f u n c t i o n b l o c k f i gu r e 3 . f u n c t i o n b l o c k d i a g r a m o f t y p i c a l a pp li c a t i o n c i r c u i t f i g u r e 4. t y p i c a l a p p li c a t i o n c i r c u it ( v i n= 8 v ~ 36 v , v ou t = 5 v / 3.1 a ) CX8517 CX8517 CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 4 o r d er i n g i n f o r m a t i o n p a r t n u m b e r m a r k i n g i d l e a d f r ee l e a d f r ee p a c k i n g t y p e p a c k age t e m p e r a t u r e r a n g e e 1 e 1 2500 u n i t s o n t a p e & r e e l p b - f r ee p r o d u c t s , a s d e s i g n a t e d w i t h e1 ! s u f f i x i n t h e p a r nu m b e r , a r e r o h s c o m p li a n t . a b s o l u t e m ax i m um r a t i n gs n o t e1 ! p a r a m e t e r s y m b o l v a l u e u n i t i n pu t v o l t a g e v i n - 0 . 3 t o 40 v f ee d b a c k p i n v o l t a g e v fb - 0 . 3 t o v i n v o u t p u t s w i t c h p i n v o l t a g e v o u t p ut - 0 . 3 t o v i n v p o w e r d i s s i p a t i o n p d i n t e r n a l l y l i m i t e d m w t h e r m a l r e s i s t a n c e ( s o p 8 - e p ) ( j u n c t i o n t o a m b i e n t , n o h e a t s i n k , f r ee a i r) r ja 60 # c / w o p e r a t i n g j u n c t i o n t e m p e r a t u r e t j - 40 t o 125 # c s t o r a g e t e m p e r a t u r e t s tg - 65 t o 150 # c l ea d t e m p e r a t u r e ( s o l d e r i n g , 10 s ec ) t le ad 260 # c e s d ( h b m ) > 2000 v n o t e 1: s t r e ss e s g r ea t e r t h a n t h o s e li s t e d u n d e r m a x i m u m r a t i n g s m a y c a u s e p e r m a n e n t d a m a g e t o t h e d e v i ce . t h i s i s a s t r e ss r a t i n g o n l y a n d f u n c t i o n a l o p e r a t i o n o f t h e d e v i c e a t t h e s e o r a n y o t h e r c o n d i t i o n s a b o v e t h o s e i n d i ca t e d i n t h e op e r a t i o n i s n o t i m p l i e d . e x p o s u r e t o a b s o l u t e m a x i m u m r a t i n g c o n d i t i o n s f o r e x t e n d e d p e r i o d s m a y a f f e c t r e li a b i l i t y . CX8517 CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 5 e l ec t r i c a l c h a r a c t er i s t i c s t a = 25 ; un l e ss o t h e r w i s e s p ec i f i e d . s y m b o l p a r a m e t er t e s t c o nd i t i o n m i n. t y p. m a x. u n it s y s t e m pa r a m e t e rs t e s t c i r c u it f i g u r e 4 v f b f ee d b a c k v o l t a g e v i n = 8 v t o 36 v , v o u t = 5 v i l o a d = 0 . 5 a t o 3 . 5 a 1 . 225 1 . 25 1 . 275 v e f f i c i e n c y $ v i n = 12 v , v o u t = 5 v i o u t = 3 . 1 a - 87 - % e l ec t r i c a l c h a r a c t er i s t i c s ( dc p a r a m e t e r s ) v i n = 12 v , gnd = 0 v , v i n & gnd p a r a ll e l c o n n e c t a 100u f / 50 v ca p a c i t o r ; i o u t = 500 m a , t a = 25 ; t h e o t h e r s f l o a t i n g u n l e s s o t h e r w i s e s p e c i f i e d . p a r a m e t e r s s y m b ol t e s t c o nd i t i o n m i n. t y p. m a x. u n i t i n pu t o p e r a t i o n v o l t a g e v i n 8 36 v q u i e s c e n t s upp l y c u rr e nt i q v fb = v i n 2 . 1 5 m a o s c i ll a t o r f r e qu e n c y f o s c 144 180 216 k h z o u t p u t s h o r t f r e qu e n c y f o s p 48 k h z s w i t c h c u rr e n t l i m i t i l v fb = 0 5 a e n p i n t h r e s h o l d v en h i g h ( r e g u l a t o r on ) l o w ( r e gu l a t o r o ff ) 1 . 7 1 . 1 v m a x . d u t y c y c l e d m ax v fb = 0 v 100 % o u t p u t p o w e r p m o s r d s o n v fb = 0 v , v i n = 12 v , i sw = 3 . 5 a 60 80 m o h m CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 6 t y p i c a l s y s t e m a p p li c a t i o n ( v o u t =5 v / 3 . 1 a ) f i gu r e 5 . s y s t e m p a r a m e t e r s t e s t c i r c u i t ( v i n = 8 v ~36 v , vou t = 5 v / 3 . 1 a) 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 1 . 2 1 . 4 1 . 6 1 . 8 2 . 0 2 . 2 2 . 4 2 . 6 2 . 8 3 . 0 3 . 2 3 . 4 3 .6 0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5 4 .0 4 .5 5 .0 5 .5 output v o l t a ge v s o u t p u t c u r rent o u t p u t v o l t ag e ( v) o u t p u t c u r ren t ( a) v i n = 12 v , v o u t = 5 v , rc s = 19k v i n = 24 v , v o u t = 5 v , rc s = 19k f i gu r e 6 . s y s t e m o u t p u t c o n s t a n t c u rr e n t c u r v e CX8517 CX8517 CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 7 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 1 . 2 1 . 4 1 . 6 1 . 8 2 . 0 2 . 2 2 . 4 2 . 6 2 . 8 3 . 0 3 . 2 3 .4 40 45 50 55 60 65 70 75 80 85 90 95 100 e ff i c i e n c y v s l o a d c u r r e nt e ff i c ie n c y ( %) l o a d c u rr e n t (a) v in = 8 v , v o u t = 5v v in = 1 2 v , v o u t = 5v v in = 2 4 v , v o u t = 5v v in = 3 6 v , v o u t = 5v f i gu r e 7 . s y s t e m e ff i c i e n c y c u r ve 0 2 4 6 8 10 12 14 16 18 20 0 .0 0 .2 0 .4 0 .6 0 .8 1 .0 1 .2 1 .4 1 .6 1 .8 2 .0 2 .2 2 .4 2 .6 2 .8 3 .0 3 .2 3 .4 outp u t c u rre n t v s rcs o u t pu t c u r ren t ( a) rc s ( k o h m) vin=12v,vout=5v vin=24v,vout=5v i ou t = 1 .0a,r c s = 5k i ou t = 2 .1a,r c s = 11k i ou t = 3 .1a,r c s = 19k f i gu r e 8 . rc s v s o u t p u t c u rr e n t s e l ec t c u r v e CX8517 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 8 s c h o tt k y d i o d e s e l ec t i o n t a b l e c u rr e nt s u r f a c e m o u n t t h r o ug h h o l e v r ( t h e s a m e a s s y s t e m m a x im u m i npu t v o l t a g e ) 20 v 30 v 40 v 50 v 60 v 1 a 1 n 5817 1 n 5818 1 n 5819 1 n 5820 1 n 5821 1 n 5822 m br 320 m br 330 m br 340 m br 350 m br 360 s k 32 s k 33 s k 34 s k 35 s k 36 30 w q 03 30 w q 04 30 w q 05 31 dq 03 31 dq 04 31 dq 05 3 a s r 302 s r 303 s r 304 s r 305 s r 306 1 n 5823 1 n 5824 1 n 5825 s r 502 s r 503 s r 504 s r 505 s r 506 s b 520 s b 530 s b 540 s b 550 s b 560 s k 52 s k 53 s k 54 s k 55 s k 56 5 a 50 w q 03 50 w q 04 50 w q 05 CX8517 www.yxwic.com
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d a t a s h eet 3. 5 a 1 8 0 k h z 36 v b u c k d c t o d c c o n v e r t e r wi t h c v / cc l o o p 9 p ac k a g e i n f o rm at i o n p a c k ag e i n f o r m a t i o n ( s o p 8 - e p ) CX8517 www.yxwic.com
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